1. Field of the Invention
The present invention relates to a temperature control valve that has no moving parts for regulating the temperature of a fluid, either liquid or gas, at the output of a heat exchanger.
2. Description of the Prior Art
The control of temperature in a fluid system containing a heat exchanger, e.g., radiator, boiler, furnace, is of fundamental importance for industrial, military and commercial applications. Generally, such systems rely on temperature sensitive probes, such as thermostats and thermocouples, as a means to control the motion of an actuator attached to a valve. These systems contain moving parts which are inherently prone to failure and require periodic maintenance. Additionally, these systems require an additional source of energy, e.g., electric, hydraulic, or pneumatic, to drive an actuator which controls the valve opening.
Other types of temperature control systems include the use of a volume of liquid with a high thermal expansion coefficient such as a hydrocarbon or silicone. The liquid is contained in bellows and the expansion is converted into a linear displacement to control a valve. This approach eliminates the need for an external energy source but requires a reliable seal for the liquid.
Still other types of control systems utilize fluidic circuits. U.S. Pat. Nos. 3,837,571 to Waeldner et al., U.S. Pat. No. 4,196,626 to Manion et al., U.S. Pat. No. 4,211,363 to Osheroff, and U.S. Pat. No. 4,276,895 to Drzewiecki illustrate control systems employing fluidic circuits and/or components. U.S. Pat. No. 3,631,873 to Swithenbank illustrates a fluid flow control arrangement for a heat exchanger in which first and second fluids are directed alternately to a common element such as a heat exchange surface by means of flow control devices of the fluid logic type so as to avoid the use of mechanical valves and to facilitate operation at high temperature. The above patents provide a means of temperature control with moving parts, or are not specifically designed for temperature control. None of the above provides a means of temperature control without moving parts.
Despite the existence of such technology, there remains a need for a control valve system for regulating the temperature of a fluid at the output of a heat exchanger.